ADWARE can cause strange mannerisms of web browsers on your PC - pop ups of web pages with suspicious commercial content
- or automatic redirection of your home page to another one ( erotica, warez, etc. )
These malware programs are installed when you browse some Internet pages of commercial content
(mainly erotics, warez, music downloads).These programs are not viruses and thats why they even can't
be detected by antivirus programs.

Dialers can take over the modem of a dial-up user, and dial long distance access numbers that can generate phone bills
of exhorbitant amounts. This type of malware is still out there, and broadband users can be affected if their phone
lines are still connected to their computers even though their internet is supplied by a LAN connection.
These programs were most often seen in sports and gambling pages, where a pop-up box asks if you would like to view
updated information. If you click yes, it hangs up your connection to your local internet provider and dials overseas
or a 1-900 number to get the information.

A firewall is a system that prevents unauthorized access to your computer.
A firewall can be either hardware or software. Hardware firewalls provide a strong degree of protection
from most forms of attack coming from the outside world and can be purchased as a stand-alone product or in
broadband routers. Unfortunately, when battling viruses, worms and trojans, a hardware firewall may be less
effective than a software firewall, as it could possibly ignore embedded worms in out going e-mails and see
this as regular network traffic. For individual home users, the most popular firewall choice is a software firewall.
A good software firewall will protect your computer from outside attempts to control or gain access your computer,
and usually provides additional protection against the most common trojan programs or e-mail worms.
It is important to remember that on its own a firewall is not going to rid you of your computer virus problems,
but when used in conjunction with regular operating system updates and a good anti-virus scanning software,
it will add some extra security and protection for your computer or network.

A computer (or node) on a network that serves as an entrance to another network. In enterprises, the gateway is the computer
that routes the traffic to/from a workstation (on the internal or LAN - Local Area Network) to the outside network (WAN - Wide Area Network) that is serving Web pages. In homes, the gateway
is often the ISP that connects the user to the internet. In enterprises, the gateway node often acts as a proxy server and a
firewall. The gateway is also associated with both a router, which use headers and forwarding tables to determine where
packets are sent, and a switch, which provides the actual path for the packet in and out of the gateway.

Also referred to as TCP session hijacking, a security attack on a user session over a protected network.
The most common method of session hijacking is called IP spoofing, when an attacker uses source-routed IP packets
to insert commands into an active communication between two nodes on a network and disguising itself as one of the
authenticated users. This type of attack is possible because authentication typically is only done at the start of a
session.
Another type of hijacking involves your web browser, when you click on a link to get to a page, and you end up at a pre-determined site that has nothing to do with your request. This type of malware is usually associated with gambling sites.

A keylogger is a type of surveillance software (considered to be either software or spyware) that has the capability
to record every keystroke you make to a log file (usually encrypted). A keylogger recorder can record instant messages
e-mail, and any information you type at any time using your keyboard. The log file created by the keylogger can then be
sent to a specified receiver. Some keylogger programs will also record any e-mail addresses you use and Web site URLs
you visit. Keyloggers, as a surveillance tool, are often used by employers to ensure employees use work computers
for business purposes only. Unfortunately, keyloggers can also be embedded in spyware allowing your information
to be transmitted to an unknown third party

The act of sending an e-mail to a user falsely claiming to be an established legitimate enterprise in an attempt to scam the user into surrendering private information that will be used for identity theft.
The e-mail directs the user to visit a Web site where they are asked to update personal information, such as passwords and credit card, social security, and bank account numbers, that the legitimate organization already has.
The Web site, however, is bogus and set up only to steal the user's information.
For example, 2003 saw the proliferation of a phishing scam in which users received e-mails supposedly from eBay claiming that the user's account was about to be suspended unless he clicked on the provided link and updated the credit card information that the genuine eBay already had.
Because it is relatively simple to make a Web site look like a legitimate organizations site by mimicking the HTML code, the scam counted on people being tricked into thinking they were actually being contacted by eBay and were subsequently going to eBay's site to update their account information. By spamming large groups of people, the "phisher" counted on the e-mail being read by a percentage of people who actually had listed credit card numbers with eBay legitimately.
Phishing, also referred to as brand spoofing or carding, is a variation on "fishing," the idea being that bait is thrown out with the hopes that while most will ignore the bait, some will be tempted into biting.

Potentially Unwanted Program files are not detected as a virus, even though they sometimes act very similarly.
These programs are installed legitimately when as a part of another program (often designated as an "AD-Supported program")
in which the End User License Agreement (E.U.L.A.) typically prompts a user to accept the desired program,
an additional program (Potentially Unwanted Program) is also selected to be installed.
These can sometimes be described as Browser Helper Objects (aka Search Bar Tools).
Anti-Virus programs can detect some Potentially Unwanted Programs and remove the files, although they are not primarily
designed to do so. Anti-Spyware programs are intended as a source of valuable information that there is a potential threat
on your PC which probably needs to be removed.

Electronic junk mail or junk newsgroup postings. Some people define spam even more generally as any unsolicited
e-mail. Spam is generally e-mail advertising for some product sent to a
mailing list (aka Unsolicited Commercial E-Mail or U.C.E.)
In addition to wasting people's time with unwanted e-mail, spam also eats up a lot of network bandwidth.
There is some debate about the source of the term, but the generally accepted version is that it comes from the
Monty Python song, "Spam spam spam spam, spam spam spam spam, lovely spam, wonderful spam…" Like the song,
spam is an endless repetition of worthless text.

Spyware are programs which use the internet to send information (such as list of visited web pages or installed
applications) from your PC without the knowledge/consent of the owner/user.
This activity is usually explained away as an attempt for finding out the needs and interests of users and use them
for targeted advertisements. However, nobody can secure this information or know how this technology will be abused.
Spyware is bundled with many shareware programs and the creators of these applications know about it.
It is often done to pay for the download bandwidth used to share the program.

A destructive program that masquerades as another application. Unlike viruses, trojans do not replicate themselves
but they can be just as destructive. One of the most insidious types of trojans is a program that claims to rid your
computer of viruses but instead introduces viruses onto your computer.

During the past few years, there have been many computer viruses, especially "worm" type viruses,
which are distributed by e-mail. This has caused a panic for users, which is further compounded by VIRUS HOAX messages,
which are NOT based on truth.
These false-alarm messages are usually composed using the same scheme: Warning of some extremely dangerous,
dramatically spreading virus and followed by a demand of some user action. In most cases, they ask the user to forward
the message to everyone in the user's contact list (i.e. "chain e-mail"), which causes the e-mail system to collapse
because of overload. In a worse case scenario, these messages ask users to delete the suspicious virus, altough the
file is actually a CORRECT system file. Deleting such files may lead to serious problems - some programs will no
longer work, or the whole system may crash.

A program or piece of code explicitly designed to be loaded onto your computer without your knowledge and
executes against your wishes. Viruses are also self-replicating. A virus that can rudundantly copy itself is easy to produce.
Even a simple virus is dangerous because it will quickly use all available memory and crash the computer.
A more dangerous virus is one capable of transmitting itself to distant computers via e-mail or direct connection.

A worm is similar to a virus by its design, and is considered to be a sub-class of a virus.
Worms spread from computer to computer, but unlike a virus, it has the capability to travel without any help from a person.
A worm takes advantage of file or information transport features on your system, which allows it to travel unaided.
The biggest danger with a worm is its capability to replicate itself on your system, so rather than your computer sending out
a single worm, it could send out hundreds or thousands of copies of itself, creating a huge devastating effect.
One example would be for a worm to send a copy of itself to everyone listed in your e-mail address book.
Then, the worm replicates and sends itself out to everyone listed in each of the receiver's address book,
and the cascade continues on down the line. Due to the copying nature of a worm and its capability to travel
across networks the end result in most cases is that the worm consumes too much system memory (or network bandwidth),
causing Web servers, network servers and individual computers to crash. In more recent worm attacks such
as the much-talked-about Blaster Worm, the worm has been designed to tunnel into your system and allow malicious
users to control your computer remotely.